This invention relates to enclosures, and, more particularly, to sheet metal enclosures for machine tools, machinery and other applications.
Many machines require an enclosure or shroud to protect the machines from contamination from the environment and/or to protect workers from the machines during operation. For example, machine tools intended to perform boring, turning, facing, grooving or other metal working operations often require shrouds to protect the operator from the coolant spray, the metal chips formed in the course of the machining operation or portions of the cutting insert which may fracture and be thrown from the machine in the event of failure of the insert.
Shrouds or enclosures for machine tools and other machinery are usually formed of sheet metal and compromise opposed sidewalls, opposed endwalls, a top and a bottom interconnected at the corners. Typically, flanges are formed by bending the ends of each sidewall and endwall where they meet to form the corners of the shroud, and a series of mounting holes are drilled in each flange which receive metal screws for attaching the sidewalls to the endwalls. The same means of attachment can be used to connect the top and bottom sections to the sidewalls and endwalls.
Prior art sheet metal enclosures or shrouds made in this fashion have several disadvantages. Relatively close tolerances must be maintained in the formation of the bends in the wall sections at the corners of the shroud, and in the location of the mounting holes therealong, or substantial difficulties can arise in the assembly operation. If the corner sections of the walls are not bent properly to form the flanges or if the mounting holes are not drilled at the same intervals along each corner flange, it is extremely difficult to properly align the mounting holes of one wall with the mounting holes of another wall to insert the metal screws. Often the corners of the walls must be bent and forced together in order for the mounting holes to align. This requires the labor of two or more individuals, one to align the wall sections and the other to insert the metal screws, which substantially increases the costs of assembly of such prior art shrouds.
Problems with prior art shrouds of the type described above are also encountered during disassembly for maintenance or any other purpose. The metal screws are easily worn when threaded into and out of the mounting holes, and can become lost when the shroud is disassembled. Additionally, a large number of mounting screws are often required to securely interconnect the walls, top and bottom of the shroud which require a substantial amount of time to remove when access to the interior of the shroud is desired.
Another problem with prior art shrouds is that they can be noisy, particularly if the machinery housed by the shroud vibrates while operating. The metal screws connecting the corners of the walls are often loosened by the vibrations causing the screws to rattle within the mounting holes. If the screws loosen enough to allow the flanges at the corners of the shroud to separate, the walls vibrate against one another creating further noise.